The installation of crown molding is probably the most difficult task for an artisan in the building industry. The majority of crown molding is cut on a power miter saw that has compound adjustments for table and bevel cutting angles. Many saws will have marked compound angle settings for 90 degree corners. When cutting anything other than an inside or outside 90 degree corner, the worker has to calculate the compound degree settings, use a specially prepared reference table, or work by trial and error.
There are two types of crown molding used in the building industry with spring angles of 45 degrees and 38 degrees. The “spring angle” is the angle at which the rear face of the crown molding sits between the ceiling and wall. A spring angle of 45 degrees extends out from the wall at an angle of 45 degrees and upward to contact the ceiling. Therefor, the distance from the wall contact of the molding to the ceiling is the same as the distance from the wall to the ceiling contact. With a spring angle of 38 degrees, the rear face of the molding extends out from the wall at an angle of 38 degrees and upwardly to contact the ceiling at a 52 degree angle. Here, the distance from the wall contact of the molding to the ceiling is greater than the distance from the wall to the ceiling contact.
There are two systems for cutting crown molding with a miter saw. Crown molding can be cut by the “stand-up” system”, with the molding oriented on the miter saw just as it will be installed against a wall. In this system, the table angle is simply set at the miter angle and there is no adjustment for bevel. Cutting accuracy suffers with the “stand-up” system because it is difficult to hold the molding in the proper orientation. This system is also discouraged for operator safety considerations.
The “flat” system for cutting crown molding, with the molding laid flat on the saw table, involves a compound miter angle. The saw table and bevel are set at calculated values that may be derived by reference to a chart or handbook. This system is the preferred in the building industry for safety and accuracy
There are a number of protractors and squares on the market in home centers that provide simple miter angles for trim and moldings. Crown moldings present a different problem. Most products specifically designed for cutting crown molding by the flat system require the user to first determine the angle between the walls at a corner and then, refer to a chart or handbook in order to find the compound settings for their miter saw. This is time consuming and introduces the potential for error. Since errors are only discovered when the pieces are cut and installed, both time and materials can be wasted. Protractor-like measuring tools currently available to the construction industry give the angle between the walls and then require the user to refer to the aforementioned chart.
A first object of the present inventions therefore, is to provide a simple tool for determination of saw table and bevel angle values for installing crown moldings on a wide range of wall corner angles. A second object is to eliminate the need for measuring and transferring corner angles to a chart and perhaps, interpolating between corner angle readings for accurate settings. A third object is to eliminate the potential for wasted time and materials in the installation of crown molding.